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Synthesis of Natural (−)-Antrocin and Its Enantiomer via Stereoselective Aldol Reaction

Venkatachalam Angamuthu, Dar-Fu Tai
2020 Molecules  
The total synthesis of (−)-antrocin and its enantiomer are presented.  ...  and pyridinium chlorochromate (PCC) oxidation for synthesis of essential lactone core in (−)-14; and (d) non-basic Lombardo olefination of the carbonyl at the final step to yield (−)-antrocin.  ...  Conflicts of Interest: The authors declare there are no conflict of interest. Molecules 2020, 25, 831  ... 
doi:10.3390/molecules25040831 pmid:32075004 pmcid:PMC7070359 fatcat:vnn5ybabzfazddg44cmgxlczxu

Multi-Catalytic Route for the Synthesis of (S)-Tembamide

Laura Leemans, Marc D. Walter, Frank Hollmann, Anett Schallmey, Luuk M. van Langen
2019 Catalysts  
To achieve hydrogenation of the nitrile moiety with highest chemoselectivity and enantioretention, various parameters such as nature of the catalyst, reaction temperature and hydrogen pressure were studied  ...  Enantiopure β-amino alcohols constitute one of the most significant building blocks for the synthesis of active pharmaceutical ingredients.  ...  Conflicts of Interest: The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results  ... 
doi:10.3390/catal9100822 fatcat:7wllze4sljfxfa7d7yktdhz5ye

Intramolecular hydrogen bonding and tautomerism in Schiff bases: Part VI. Syntheses and structural investigation of salicylaldimine and naphthaldimine derivatives

Selen Bilge, Zeynel Kiliç, Zeliha Hayvali, Tuncer Hökelek, Serap Safran
2009 Proceedings of the Indian Academy of sciences. Chemical sciences  
The UV-vis spectra of the Schiff bases have been systematically studied in organic solvents of different polarity, acidic and basic media and found useful in understanding of tautomeric equilibria ( phenol-imine  ...  The molecular structure of 8 has been determined crystallographically, and observed that the compound is in the form of phenol-imine, defined by the strong intramolecular [O-H...N = 1⋅72(3), 1⋅81(2) Å]  ...  Acknowledgements The authors wish to acknowledge Ankara University Research  ... 
doi:10.1007/s12039-009-0128-2 fatcat:ezxzoezyqrgkpmemv4vshre4fq

High-resolution NMR structure of an RNA model system: the 14-mer cUUCGg tetraloop hairpin RNA

Senada Nozinovic, Boris Fürtig, Hendrik R. A. Jonker, Christian Richter, Harald Schwalbe
2009 Nucleic Acids Research  
Here, we discuss the impact of various NMR restraints on structure quality and discuss in detail the dynamics of this system as previously determined.  ...  The extraordinary high precision of the structure (root mean square deviation of 0.3 Å ) could be achieved by measuring and incorporating all currently accessible NMR parameters, including distances derived  ...  A variety of NMR parameters reflect on the dynamic structure of RNA oligonucleotides in solution, and direct monitoring of persistent hydrogen-bonding interactions in RNA and DNA is a particular strength  ... 
doi:10.1093/nar/gkp956 pmid:19906714 pmcid:PMC2811024 fatcat:zmtna7j5szgmxnnyhpz5c3raze

TROSY and CRINEPT: NMR with large molecular and supramolecular structures in solution

Roland Riek, Konstantin Pervushin, Kurt Wüthrich
2000 TIBS -Trends in Biochemical Sciences. Regular ed  
Acknowledgements We obtained financial support from the Schweizerischer Nationalfonds (Project 31.49047.96).  ...  (d) One-dimensional cross sections along the 3 ( 1 H) axis of 3D TROSY-HCN (Ref. 16) and conventional three-dimensional HCN (Ref. 27) experiments.  ...  This, together with the chemical shift, is the most important NMR parameter for routine studies of chemical structures.  ... 
doi:10.1016/s0968-0004(00)01665-0 pmid:11050425 fatcat:nv3y65iscjbkveeyurglgfwi7u

Tetrahedral Assembly with Lanthanides: Toward Discrete Polynuclear Complexes

Josef Hamacek, Gérald Bernardinelli, Yaroslav Filinchuk
2008 European Journal of Inorganic Chemistry  
S7 L is the binding affinity related to the connection between one coordination site and one metal ion, u LL and LnLn u hold for interligand and intermetallic interactions, eff c is the effective concentration  ...  The molecular structure of the two independent [Tb 4 (L) 4 ] complexes in the asymmetric unit is similar to those one reported here but the poor data to parameter ratio does not allow to obtain better  ... 
doi:10.1002/ejic.200800455 fatcat:xytrqud335akpbam7fqep77fg4

Preparation of partially 2H/13C-labelled RNA for NMR studies. Stereo-specific deuteration of the H5'' in nucleotides

J. Cromsigt
2002 Nucleic Acids Research  
The stereo-specific deuteration of the H5′′ immediately provides the stereo-specific assignment of H5′ resonances in NMR spectra, giving access to important structural parameters.  ...  An effective in vitro enzymatic synthesis is described for the production of nucleoside triphosphates (NTPs) which are stereo-specifically deuterated on the H5′′ position with high selectivity (>98%),  ...  This study was supported by grants from the Structural Biology Network of the Strategic Research in Sweden (SSF), Swedish National Research Council, Bioteknik Medel, Umeå University Sweden  ... 
doi:10.1093/nar/30.7.1639 pmid:11917025 pmcid:PMC101849 fatcat:lbz5ucahojeojnhdoktmkzrucu

Preparation, Characterization and Biological Activity of New Tridentate Imine-Oxime Ligand (H2L) and Its Metal Complexes

Basim H. Al-Zaidi, Ahmed H. Ismail, Ali N. Naseaf, Wessal Khamis
2018 Asian Journal of Chemistry  
RESULTS AND DISCUSSION 1 H NMR and 13 C NMR spectra of H2L: The chemical shifts data and their assignments of both NMR spectra were listed, respectively (Tables 1 and 2) . 1 H NMR spectrum of H2L exhibited  ...  to H1, H2, H7, H6, H3,H5 and H4, respectively.  ...  DMSO has been used as blank control solvent, because it is inactive in culture medium. The concentration (1 × 10 -4 M), didn't show activity toward any one of selected bacteria.  ... 
doi:10.14233/ajchem.2018.21257 fatcat:bqstoxx6cbh3zmk66zvtm7rbse

Ammonia: the molecule for establishing 14N and 15N absolute shielding scales and a source of information on nuclear magnetic moments

Wlodzimierz Makulski, Juan J. Aucar, Gustavo A. Aucar
2022 Journal of Chemical Physics  
The application of a new scheme to introduce the most important electronic effects on NMR shieldings, together with highly accurate quantum chemical calculations allow the 14/15N and 1H shielding of the  ...  Multinuclear NMR studies of the gaseous mixtures 3He/14NH3 and 3He/15NH3 are reported. Precise analysis of the 3He, 14N, 15N and 1H resonance frequencies show linear dependence on the gas density.  ...  effects are introduced to obtain the semi-experimental absolute shielding constants of lightatoms like 17 O in H2O and 33 S in H2 33 S.  ... 
doi:10.1063/5.0096523 fatcat:blw3j27rvzbcvewxiuhceqxb2u

Solution Structure and Conformational Dynamics of Deoxyxylonucleic Acids (dXNA): An Orthogonal Nucleic Acid Candidate

Mohitosh Maiti, Vanessa Siegmund, Mikhail Abramov, Eveline Lescrinier, Helmut Rosemeyer, Mathy Froeyen, Amutha Ramaswamy, Arnout Ceulemans, Andreas Marx, Piet Herdewijn
2011 Chemistry - A European Journal  
Here we present the solution structure and conformational behavior of two self-complementary, fully modified dXNA oligonucleotides as determined by CD and NMR spectroscopy.  ...  These studies are the initial experimental proof for structural orthogonality of dXNA and also try to answer the question 'why deoxyribose and not deoxyxylose' as natural information system.  ...  Leuven grants (IDO and GOA) and partially by the DFG. We are grateful to Dr. Koen Nauwelaerts for helpful discussions. We thank Prof.  ... 
doi:10.1002/chem.201102509 pmid:22180030 fatcat:dogjlqzqcbalnbt7lnvfc2zlni

Solution structure of a purine rich hexaloop hairpin belonging to PGY/MDR1 mRNA and targeted by antisense oligonucleotides

Flore Joli, Nadia Bouchemal, Alain Laigle, Brigitte Hartmann, Edith Hantz
2006 Nucleic Acids Research  
This hairpin is studied by multidimensional NMR and restrained molecular dynamics, with special emphasis on the conformation of south sugars and non-standard phosphate linkages evidenced in both the stem  ...  and the loop.  ...  Simenel and M. Delepierre (Pasteur Institut) are gratefully acknowledged for providing NMR facilities to perform the TROSY-HCN experiment used in this work. The authors thank R.  ... 
doi:10.1093/nar/gkl617 pmid:17041234 pmcid:PMC1694020 fatcat:idkbhqzgnjay7oakemzao4noz4

The Impact of Delayed Storage on the Measured Proteome and Metabolome of Human Cerebrospinal Fluid

T. Rosenling, M. P. Stoop, A. Smolinska, B. Muilwijk, L. Coulier, S. Shi, A. Dane, C. Christin, F. Suits, P. L. Horvatovich, S. S. Wijmenga, L. M. C. Buydens (+5 others)
2011 Clinical Chemistry  
Metabolome analysis was performed at 3 laboratories by NMR, GC-MS, and LC-MS. Targeted analyses of cystatin C and albumin were performed by LC-tandem MS in the selected reaction monitoring mode.  ...  CONCLUSIONS: The measured proteome and metabolome of centrifuged human CSF is stable at room temperature for up to 2 hours.  ...  Acknowledgments: The authors thank Prof. Dr. Rogier Hintzen from the Department of Neurology, Erasmus University Medical Center, Rotterdam, the Netherlands, for providing the CSF samples.  ... 
doi:10.1373/clinchem.2011.167601 pmid:21998343 fatcat:xe6excts7jfx3n3gomrf4ngo7u

Synthesis, physicochemical, thermal, fluorescence and catalytic activity studies of novel Mn(II), Co(II), Ni(II) and Cu(II) complexes with tridentate (ONS) Schiff base ligand

Manara Ahmed Ayoub, Eman Hamed Abd-Elnasser, Mona Abdel-Aziz Ahmed, Marium Girgis Rizk
2017 European Journal of Chemistry  
and study the effect of solvent and pH on it.  ...  The kinetic thermodynamic parameters such as E*, H*, S* and G* were determined for each thermal degradation stage of TG curves of the metal(II) complexes using Coat-Redfern method.  ...  Effect of solvent and pH The influence of the solvent on Schiff base ligand HL and its metal(II) complexes were studied.  ... 
doi:10.5155/eurjchem.8.1.85-95.1513 fatcat:gj67uvunlbhtbn2zgrwmcmojqm

The structure of an enzyme-activating fragment of human telomerase RNA

2005 RNA: A publication of the RNA Society  
Previous work on telomerase has shown that deletion of the hTR J6 asymmetric internal loop results in an RNA incapable of binding the enzymatic protein component of the RNP and therefore an inactive RNP  ...  Here we report the NMR structure of a functionally essential RNA structural element derived from the human telomerase RNA CR4-CR5 domain.  ...  Spectrometer time and the assistance of Nancy Isern at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), Richland, Washington, were greatly appreciated.  ... 
doi:10.1261/rna.7222505 pmid:15703438 pmcid:PMC1370729 fatcat:rs57jcj7cjgy7pjwdr4orludjq

Solution structure of the 5′-terminal hairpin of the 7SK small nuclear RNA

Sarah Bourbigot, Anne-Catherine Dock-Bregeon, Pascal Eberling, Jérôme Coutant, Bruno Kieffer, Isabelle Lebars
2016 RNA: A publication of the RNA Society  
The HPI solution structure displays an elongated shape featuring four helical segments interrupted by one internal loop and three bulges with distinct folds.  ...  Hexim1 and Tat proteins both comprise conserved and similar arginine-rich motifs that were identified to bind the 7SK RNA at a repeated GAUC site located at the top of the 5 ′ -terminal hairpin (HPI).  ...  .); by the French Infrastructure for Integrated Structural Biology (FRISBI) (ANR-10-INSB-05-01); and by Instruct, as part of the European Strategy Forum on Research Infrastructures (ESFRI) and through  ... 
doi:10.1261/rna.056523.116 pmid:27852926 pmcid:PMC5113205 fatcat:a5d4ms6ernfrbbu77trya6xdge
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